The goal of this program project grant is to increase our understanding of certain effects of age on endocrine function. Two projects are closely related, one investigating the cause of the age-related deterioration of glucose tolerance, and the other attempting to relate these changes to hemoglobin glycosylation. Other studies involve the effect of age on gonadal function and sexual behavior in the rat, changes in glucocorticoid and vitamin D binding to intestine that occur with age, and the effect of age on somatomedin binding and function.